Stock Keeping Units (SKU) are product codes for internal company use. SKUs are unique to different companies. SKUs are alphanumeric codes used to internally track product inventory and products sold. Each company chooses distinct SKU numbers.


Universal Product Codes (UPCs) are 12 digit product codes for external use. UPCs are standardized tracking codes. UPCs will be the same everywhere. UPCs remain constant throughout a product's shelf life.


Barcodes are codes designed for machines, such as scanners and are comprised of numbers and parallel lines. Barcodes are used by businesses to easily track products, prices, and stock.